1. Technical Field
The invention relates to a plain bearing composite material and production methods therefore.
2. Related Art
Known from DE 44 15 629 C 1 is the use of a copper-nickel-silicon alloy for producing wear-resistant objects with emergency running properties such as, for example, cast pistons for pressure casting machines. The alloy described in DE 44 15 629 C1 consists of 1-4% nickel, 0.1-1.5% silicon with the remainder being copper, and is used as a solid material.
U.S. Pat. No. 2,137,282 describes an alloy comprising 0.1-30% nickel, 0.05-3% silicon and the remainder copper. Following appropriate heat treatment, this alloy is distinguished by high hardnesses and good electrical conductivities.
U.S. Pat. No. 1,658,186 describes a copper-nickel-silicon alloy, where silicides acting as hard particles are discussed in detail. Various heat treatment methods are also specified for adjusting the hardness.
Another copper-nickel-silicon alloy is found in U.S. Pat. No. 2,241,815 where the nickel fraction is 0.5-5% and the silicon fraction is 0.1-2%.
U.S. Pat. No. 2,185,958 describes alloys comprising 1% nickel, 3.5% silicon and the remainder copper as well as 1.5% silicon and 1% nickel and the remainder copper.
DE 36 42 825 C1 discloses a plain bearing material comprising 4 to 10% nickel, 1-2% aluminium, 1-3% tin and the remainder copper as well as the usual impurities, which should have a high strength and long lifetime. Solid material bushings are produced from this plain bearing material.
GB 2384007 describes a plain bearing composite material with a steel back on which a sintered layer of a copper alloy is applied, having a maximum hardness of 130 HV. The copper alloy comprises 1-11 wt. % tin, up to 0.2 wt. % phosphorus, maximum 10 wt. % nickel or silver, maximum 25 wt. % lead and bismuth.
Plain bearing composite materials in which a lining is sputtered onto a bearing metal layer are provided with intermediate layers of nickel, of a nickel alloy, of nickel-chromium, of zinc or of a zinc alloy as described in DE 43 28 921 A1. If a Cu alloy is used as the bearing alloy and if an Sn-containing alloy is used for the uppermost layer, the Sn then diffuses in the course of time into the Cu alloy, thus reducing the Sn content of the uppermost layer. At the same time, a brittle CuSn compound is formed at the compound surface, thus reducing the binding strength. In view of this, the intermediate layer of Ni or an Ni alloy is formed on the bearing alloy by spraying on or sputtering or by electro-plating. The uppermost layer is then formed by vapour deposition, whereby a more stable bond can be obtained.
Diffusion barrier layers are also mentioned in DE 28 53 774.
DE 195 25 330 describes a layer material in which a bearing material is sputtered directly onto a supporting material. A steel supporting metal can be used as the supporting material to which the bearing material can be applied without an intermediate layer. However, it is also possible to use a copper-containing supporting material, in particular a supporting material comprising a copper-lead-tin alloy. For example, the supporting material can consist of CuPb22Sn.
If the lead fraction in the supporting material is of the order of magnitude of the lead fraction in the bearing material, there is no concentration gradient or only a small concentration gradient between the two materials, so that no diffusion processes can take place between the bearing material and the supporting material. If the supporting material has a higher lead concentration than the bearing material, the migration of lead to the surface of the bearing material is additionally promoted. The copper-lead-tin alloy forming the supporting material can be clad onto a steel supporting metal by casting.